NRG Energy (Princeton N.J., U.S.A.), one of the largest power operators in the U.S., formed a new company last month with the University of Delaware to test out how vehicle-to-grid (V2G) can keep a grid stable as the share of intermittent renewable energy sources rises. V2G allows electric cars to pump electricity back into the grid when power demand spikes.

In its earliest stages, the company, called eV2g, will target commercial fleets, said NRG spokesperson Lori Neuman. Fleets will provide a better test than individual car owners, since they have many electric vehicles and offer a bigger potential power supply.

Participants will plug their cars into charging stations that are linked to a grid operator's servers through a wireless system that monitors the batteries, in order to use them to balance electricity in the system. The project will use technologies patented by the University of Delaware and pioneered by Willett Kempton, a professor in the College of Earth, Ocean and Environment and director of the Center for Carbon-Free Power Integration.

Fleet vehicles participating in NRG's eV2g initiative will receive and return power at a scale of hundreds or potentially thousands of electric vehicles. Grid operators would pay eV2g for the electricity consumed during hours of peak demand, and eV2g would in turn pay E.V. owners for the service.

Initially, eV2g will work in the Northeast and will later expand into other areas, Neuman said, though she didn't list any specific states or regions.

Consumers will also eventually be asked to participate, particularly as the slow but steady adoption of the Nissan Leaf and Chevrolet Volt creates a potential new power supply. But it will take "at least a couple of years" to take the project out of the R&D phase and into commercial markets, said Neuman.

When that happens, Kempton said that drivers of E.Vs. with "high-power" batteries—such as AC Propulsion's eBox and BMW's Mini E—could earn up to $1,500 per year if their cars stay plugged when not in use.

The eV2g program will encourage participants to recharge their car batteries at night when electricity demand is lower, so as not to tax the grid and also to store unused wind power that is generated during those hours. Car owners can set their charging stations to maintain a certain level of battery life at all times, so the grid operator doesn't use too much juice and leave drivers stranded.

The eV2g initiative joins NRG's existing efforts to spur widespread electric car adoption. Through its eVgo network in Houston and Dallas-Forth Worth, the utility is working with government officials, businesses and residents to install home and public charging stations and offer fixed monthly charging plans at a rate that rivals the cost of a gasoline fill-up.

"E.V.-to-grid technology is the next logical step in the electrification of our transportation network," says Denise Wilson, president of NRG's Alternative Energy Services.

NRG Energy is not the first big utility to test out vehicle-to-grid models, though eV2g will mark the largest private investment by a power company to date, said Kempton, who would not disclose any financial details. He added that NRG is the first company in the United States to license the University of Delaware's technologies.

Other utilities, including Pacific Gas & Electric in San Francisco and Xcel Energy in Minneapolis, launched smaller V2G demonstrations several years ago, but they never moved out of the pilot stage.

In PG&E's case the project fizzled out completely after automakers expressed concern that supplying power to the grid—not just drawing it in—would prematurely wear out car batteries and force their early replacement, a company spokesperson told InsideClimate News. The battery used in most E.V. models costs $16,500—nearly half the cost of the vehicle and up to eight times more expensive than the lead acid batteries used in gas cars, say estimates.

The PG&E project also faced policy hurdles. Federal regulations do not allow individual drivers to sell battery power on the wholesale market, a limitation that still needs to be adjusted if eV2g is to expand to consumers.

While U.S.-based demonstrations move forward in fits and starts, several international projects are also progressing, including another venture led by the University of Delaware. Kempton co-founded and serves as chief technology officer for Nuvve, a Danish technology company that is deploying the university's patented V2G technology in a pilot of about 30 cars that can sell power back to the grid.

In Japan, Nissan introduced a new system for its Leaf this summer that would enable owners to connect their cars to a charging outlet and provide electricity to their homes.

U.S. utilities and researchers have yet to model a commercial-scale project using hundreds or thousands of E.V.'s on the ground, which is what the eV2g venture will try to do.